From f5307c3ba8401fbaf9008705d7f8dfa7d28e944c Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sun, 4 Dec 2022 11:54:16 -0700
Subject: [PATCH] [map] Speed up is_real()

---
 src/hb-map.hh | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/hb-map.hh b/src/hb-map.hh
index bfb1b3f76..3c75f544e 100644
--- a/src/hb-map.hh
+++ b/src/hb-map.hh
@@ -65,22 +65,25 @@ struct hb_hashmap_t
 
   struct item_t
   {
+#define HASH_BITS 29
     K key;
-    uint32_t hash : 30;
+    uint32_t hash : HASH_BITS;
     uint32_t is_used_ : 1;
     uint32_t is_tombstone_ : 1;
+    uint32_t is_real_ : 1;
     V value;
 
     item_t () : key (),
 		hash (0),
-		is_used_ (false), is_tombstone_ (false),
+		is_used_ (false), is_tombstone_ (false), is_real_ (false),
 		value () {}
 
     bool is_used () const { return is_used_; }
-    void set_used (bool is_used) { is_used_ = is_used; }
+    void set_used (bool is_used) { is_used_ = is_used; set_real (); }
     bool is_tombstone () const { return is_tombstone_; }
-    void set_tombstone (bool is_tombstone) { is_tombstone_ = is_tombstone; }
-    bool is_real () const { return is_used_ && !is_tombstone_; }
+    void set_tombstone (bool is_tombstone) { is_tombstone_ = is_tombstone; set_real (); }
+    bool is_real () const { return is_real_; }
+    void set_real () { is_real_ = is_used_ && !is_tombstone_; }
 
     template <bool v = minus_one,
 	      hb_enable_if (v == false)>
@@ -360,7 +363,7 @@ struct hb_hashmap_t
 
   item_t& item_for_hash (const K &key, uint32_t hash) const
   {
-    hash &= 0x3FFFFFFF; // We only store lower 30bit of hash
+    hash &= (1u << HASH_BITS) - 1;
     unsigned int i = hash % prime;
     unsigned int step = 0;
     unsigned int tombstone = (unsigned) -1;